Gun



0. V. PAYNE.

GUN.

APPLICATION FILED JAN. 24, I920. r

' Patented July 27, 1920.

3 SHEETSSHEET 1.

0. v. PAYNE.

sun.

APPLICATION FILED JAN. 24, 1920.

Patented July 27, 1920.

3 SHEETSSHEET 2.

O. V. PAYNE.

GUN.

APPLICATION FILED JAN-24, 1920.

Patented July 27, 1-920.

3 SHEETSSHEET 3.

W V r r y UNITED STATES PATENT OFFICE.

OSCAR v. PAYNE, or cLnvELAnn, 01-110, ASSIGNOR r0 AUTO-ORDINANCEconroim- TION', on NEW YORK, n. Y., A CORPORATION on NEW YORK.

GUN.

Specification of Letters Patent.

Patented July 27, 1920.

Application filed January 24, 1920. Serial No. 353,704.

To all whom it may concern:

Be it known that I, OSCAR V. PAYNE, a citizen of the United States, andresident of Cleveland, in the 'county of Cuyahoga and State of Ohio,have invented new and useful Improvements in Guns, of which thefollowing is a specification.

This invention relates to guns, particularly automatic guns of thesmaller types such as rifles and machine guns, more particularly to gunsof the type having a breech closure reciprocatable rearwardly andforwardly and rotatable into locked position at the forward end of itsstroke, and still more particularly to guns operating, according to thediscovery set forth in the patent, to Blish 1,131,319, granted March 9,1915, wherein the receiver and breech closure are provided with lookingabutments inclined to the line of breech pressure at such angle. thatthe closure is held closed during high breech pressure but isautomatically unlocked directly in response to the breech pressureacting through the closure when the pressure decreases to a relativelylow value.

In automatic guns of the type referred to, having a reciprocatory breechclosure arranged to rotate into locked position at the forward end ofits stroke, the purely reciprocatory movement of the closure durlng' itsrecoil must be quickly changed into a combined reciprocatory and rotarymovement at the end of its forward stroke and vice versa as the closureunlocks and opens, especially in rapid fire guns where the cycle ofoperation is repeated many times per second. Heretofore, cams or guideshave been provided on the receiver in the path of lugs on the closure,the guides extending obliquely to the line of reciprocation to throw theclosure into locked position at the end of its forward stroke, otherides being provided to stop the rotation 1n unlocking and to guide theclosure in its recoil movement. With such an arrangement a sharp impactresults eachtirne the lugs strike the oblique cams or guides at theforward end of the stroke and a still sharper impact results each timethe lugs strike the longitudinal guidesin the unlocking rotation of theclosure. These. impacts cause excessive wear and frequent breakages andmitigate against accurate firing.

Another difliculty encountered in us of the aforesaid type is that offorming the locking abutments on the boltand more especially in thereceiver, and of making these abutments of sufficient strength toWithstand the wear and tear of the breech pressures, these pressuresrising to the order of fifty thousand pounds per square inch in militaryrifles for example. v

Furth rmore it is essential that the weight of, military firearms andother portable guns be minimized to the greatest possible extent.Moreover, in guns of the aforesaid type 1t is desirable to have one ormore lugs or projections extend'outwardly from the breech mechanismthrough slots in the receiver to control the breech mechanism, and inorder to exclude dust and other foreign matter it is essential thatthese slots be closed. I Another difficulty experienced in guns of thetype referred to is that of securing uniform and reliable action. Whileknown guns of this type will function well at times, they frequentlyfunction erratically or not at all. I have discovered that thisdifiiculty can be overcome by uniformly lubricating the contactingsurfaces between the locking abutments 'of the rebeiver and breechclosure and that this lubrication does not destroy the locking qualitiesof the abutments at high breech pressure, as would be expected,presumably for the reason that the film of lubricant between theabutting 'surfacesis momentarily squeezed into the interstices of theabutments during the infinitesimal interval of high breech pressure.

The principal ob ects of the present invention are to overcome theaforesaid and other difiiculties and to provide the ,aforesaid and otheressentials. More particular objects are, viz.: smoothly to blend thereciprocatory and rotary movements of the breech closure so aspractically or wholly to eliminate the aforesaid impacts and the wearand other disadvantages incident thereto; to provide interlockingabutments on the breech closure and receiver which may be manufacturedwith facility and at alow cost, and which have extenslve bearingsurfaces and great strength, and at the sa-me'time low weights; toprovide a gun which is lighter than known of like capacities andcapabilities but which is more durable and safe; to provide means forautomatically closing the slots or other openings provided in thereceiver for projectingparts the working mechanism of the breech action;to provide means for lubricating the,

locking abutments of the receiver and breech ,closure and other slidingparts of the mechanism so as to render the automatic action of thebreech mechanism uniform and reliable and to reduce the wear; andgenerally to improve the' construction and operation of guns of theaforesaid types.

The inventionconsists in providing guns of the aforesaid types with aninterfitting lug and guideway on the bolt and receiver respectively (orvice versa) for guiding the movements of the bolt, the guideway having alongitudinal portion and a transverse portion tangentially connectingwith the longitudinal portion throughout a gradual and uninterruptedbend so that the rotation of the closure into and out of locked positionblends with its reciprocation smoothly and without impact, and the lugand guideway being coordinated with the locking abutments so that theabutments are guided into and out of locking engagement throughout asmoothly curving path without subjecting the abutments to impacts orother forces. I have discovered that these results cannot besatisfactorily attained without extending said bendcircumferentiallythroughout a relatively wide angle, preferably at leastof the order of 40 (in a gun with two sets of locking abutments) andthis angle is not available in known guns in which the total angle ofbolt rotation. is only 90 or less. I therefore propose to interrelatethe guiding lug and guideway with the locking abutments so that the boltmay be rotated through a much wider angle, preferably at least of theorder of 110, thereby affording an angle of 40 e. g. for blendingtherotation into the reciprocation and a further angle of 6. g. forinterengaging' the abutments. This involves a novel arrangement of thelocking lugs or abutments on the bolt relative to those on the receiverwhereby the two sets are angularlyspaced from each other in the unlockedposition of the bolt by an angle approximately equal to the angle ofsaid bend, that is, 40 in the example stated.

The invention also involves a shutter for closing the aforesaid slot orslots in the receiver, the shutter being nonreciprocat able butrotatable with the bolt to close the slots when the bolt is in lockedposi-.

tion and having'one. or more longitudinal slots to accommodate the lugsor other parts projecting from the breech mechanism outwardly throughthe receiver. The shutter preferably comprises a tube fitting in thereceiver tween the bolt and the inner wall of the receiver.

Another feature of the invention consists in forming the receiver intotwo parts, preferably tubular, fitted together end to end, and informing said guldeway in the form of intercommunicating slots in the twoparts. The forward part is provided with the locking abutments and theinclined portion of the guideway slot, and is made sufiiciently heavy towithstand the stresses set up by the breech pressure. The lockingabutments are preferably formed on a cylindrical sleeve or tubularmember adapted to be threaded or otherwise secured in said forward partof the receiver. The rearward part of the receiver is arranged to servemerely as a recoil housing and guide for the breech bolt and maytherefore be made relatively thin and light. Indeed it is preferablyformed as a thin tube of pressed metal, closed at its rearward end toconfine the recoil spring and threaded at its forward end to thread intothe forward part of the reoeiver'in abutting relationship with saidlocking sleeve. The shutter is also preferably formed as a pressed-metaltube adapted to fit within said rearward tubular part of the receiverwith its forwardand rearward ends abutting respectively against saidlocking sleeve and said closed end of the rearward part of the receiver.

' The forward part of the receiver and said locking sleeve are providedwith lubricant ducts leading to the abutting surfaces of the lockingabutments, wicks or other suitable lubricant feeding means beingassociated with these ducts to afford a uniform lubrimanner thelubricant may be transmitted to a part or all of the sliding surfaces ofthe breech mechanism, in addition to the locking surfaces, by beingcarried along the sliding surfaces as the parts-slide back and forth orby being supplied in such quantity as to flow over the surfaces Otherimprovements herein disclosed, such as the firing pin, triggermechanism, combined magazine and trigger guard, etc., are not claimed inthe present application and will herein be described only in connectionwith the specific embodiment of the invention illustrated in theaccompanying drawings, in which Figure 1 is a left elevation Fig. 2 is atop plan;

Fig. 3 is a left elevation, on a larger scale, of the forward part ofthe receiver;

Fig. 4 is a Vertical axial section, parts being broken away, showing thebreech closure in fully retracted position;

- Fig. 5 is a horizontal axial section showing the breech closure inlocked position;

Fig. 6 is a section similar to Fig. 4:, show- .ing the breech closure inlocked position,

andi the firing mechanism in position ready to re;

Fig. 7 is a side elevation of the ejector;

I Fig. 8 is an end elevation of the ejector;

Fig. 9 is a side elevation of a catch;

Fig. 10 is a transverse section on line 101O of Fig. 6; Fig. 11 is avertical axial section of a portion of the receiver, locking sleeve andbolt 10 with the bolt in locked position and with the firing pinremoved;

Fig. 12 is a rear elevation. of the bolt'in locked position;

Fig. 13 is a left side elevation of the safety 15 catch in safeposition;

Fig. 14 is a left side elevation of the bolt in locked position;

'Fig. '15 is a top plan of the trigger bar showing the safety catch insection in safe position;

Fig. 16 is a similar view showing the safety catch in firing position;and

Fig. 17 is a top plan of the forward end of the rearward part of thereceiver.

The particular embodiment of the invention chosen for the purpose ofillustration comprises in general a stock 1, a barrel 2, a

a receiver formed in forward and rearward parts 3 and 4, a heat guard 5surrounding the rear end of the barrel 2, the guard 5 being insulatedfrom the receiver by suitable non-conducting material 91, and a framemember 6. The forward portion 3 of the re- 7 ceiver comprisessubstantially cylindrical 5 forward and rearward ends joined together byside walls 9 and 10,the forward end being threaded over the barrel andthe rearward end being provided with internal threads to receive thelocking sleeve 11 and the rear- 40 ward portion 4 of the receiver. Aclip holder 92 is provided to facilitate loading the magazine from thetop as in the Spring field rifle; An ejection opening 13 is provided onthe right-hand side as shown in 5 Fig. 5. The frame member 6 ispreferably formed of aluminium alloy or other light metal, and has themagazine chamber 14 and also the trigger guard 15 formed integrallytherein. fThe frame member is connected to the forward part3 of thereceiver by means I of screws 16 and 17, the screw 17 having an axiallubricant duct extending therethrough,

and having a "lubricant cup 18 threaded thereover.

The locking sleeve 11, which is preferably formed of, bronze, or otherhigh pressure bearing material, is adaptedto be threaded into the part 3of .the receiver from the rear. The locking sleeve is provided onitsinner periphery with upper and lower sets '19 and 20 of locking lugswhich extend radially inwardly, the lugs of each set be- 'ing disposedin aliriement longitudinally of the gun. The forward faces of theselocking lugs are inclined circumferentially with respect toa planeperpendicular to the axis of the gun at such angles that the 'bolt lugsv abutting thereagainst will be locked thereto during high breechpressure but will slide thereover due to-'- the circumferentialobliquity of the contacting faces when the pressure drops to relativelylow value, thereby automatically unlocking the bolt according to thediscovery in the aforesaid patent to Blish. Each set of lugs 19 and 20exin the rear end of the forward portion 3 of the receiver. Disposed inthe rearward end of the tube 4 is a buffer comprising a rearward portion23 and a forward portion 24 telescoping over the rearward portion, thespace within the two portions being filled with disks 25 of leather orthe like, and the two portions being connected together by a small rod26 adapted to be compressed or flexed by impacts on the forward end ofthe buffer."

The two portions 3 and 4 of the receiver are provided withintercommunicating slots 27 and 28, the slot 28 extending longitudinallyof the rearward portion 4, and the slot 27 bending circumferentially "tothe right and connecting tangentially with the slot 28 as shown in Fig.2. The inclined portion 27 of the slot bends gradually away from thelongitudinal part; 28 through a circumferential angle of approximately40 and then continues at substantially a constant angle to a planeperpendicular to'the axis of the gun through an angle of substantially70. The forward portion 3 of the receiver is reinforced on oppositesides of the portion 27 of the slot 6 shown in Figs. 3, 4 and 6.

Rotatably fitted within the rear portion 4 of the receiver is a tubularshutter 29 abutting at its rearward end against the rear end of the tube4 through the base of the buffer, and abutting at its forward end 120against the rear end of the locking sleeve 11. This sleeve is providedwith a longitudinal slot 30 adapted to register with the longitudinalslot 28 in the receiver when the bolt is in unlocked position. The tube29-is also 125. provided with a longitudinal slot 31 oppo- (Fig. 6)fitting in groove 41 (Fig. 14) in the bolt. The extractor is providedwith a lug 93 adapted to ride in a groove 90 in the receiver and lockingsleeve, this lug serving to keep the extractor in line with the notchprovided in the barrel for the forward end thereof. Extendin from therearward end 50f the olt is an actuating. lug 37, this lug .extendingoutwardly through the slots 28 and 30 in the tubes 4 and 29. Immediatelyin advance of the enlarged head are two sets of lugs 38 and 39 adaptedto interengage with the lugs 19 and 20 on the locking sleeve 11 when thebolt is in locked position, the abutting faces of these lugs facingrearwardly in opposition to the forwardly facing lugs on the lockingsleeve. The forward end of the bolt is provided with a longitudinal slot40 (Fig. 14) decreasing in depth from front to rear and vanishing ashort distance in front of the groove 41 for the extractor, the groove40 being adapted to receive the ejector hereinafter described. The head35 of the bolt is provided with a rearwardly facing cam 42 extendingcircumferentially of the bolt through an angle of approximately 110 forthe purpose of retracting the firing member in the unlocking movement ofthe bolt as hereinafter described.

The bolt 34 is provided with an axial chamber whose diameter decreasesfrom the rear to the front by steps, and within this opening the firingpin 43 is arranged. both to rotate and to reciprocate relatively to thebolt. The firing pin bears directly on the bolt at the forward end, andat the rearward end it bears in a sleeve 44 threaded into the rearwardend of the bolt. The firing pin is provided with a depending lug 45adapted to extend downwardly through the slots 31 and 32 in the tubes 4and 29, the lug 45 being provided with a beveled cam face 46 adapted tobe enga ed by the cam 42 on the bolt.

i feature which I believe to be novel but which I do not claim in thepresent application, involves a simplified means for mounting the firingpin spring 47 on the firing pin. This means comprises a collar 48 formedintegrally with the-firing member and provided with an oblique slot 49(Fig. 6) the forward end of the firing pin spring 47 radially beingcontracted so as to engage behind this collar. By virtue of the obliqueslot 49, the contracted end of the spring 47 may be threaded over thecollar 48 from the frontin assembling the spring on the pin, the firingpin first having been inserted through the sleeve 44. After the firingpin unit is thus assembled, the sleeve 44 is threaded into the rearwardend of the bolt. The breech closure is yieldingly urged forwardly by arecoil spring 50 which fits loosely within the inner tube 29 and aroundthe buffer 24. The recoil spring is anchored to the boltat 51 and toreceiver at 52, and in putting it in place it. is subjected to a torsionwhich tends to turn the bolt in a clockwise direction into lockingposition.

The ejector comprises a tubular member 53' closed at its inner end andprovided with a flat nose 54 extending centrally from the closed end(Figs. 5, 7 and 8). This ejector is adapted to extend radially throughan opening 55 in the left side of the forward part 3 of the receiver(Figs. 3 and 5). The opening 55 extends through the receiver in theregion where the receiver changes in internal diameter, somewhat morethan the rear half of the opening extending through the portion oflarger internal diameter and somewhat less than the forward halfextending through the portion of lesser internal diameter. The openingis extended only through the wall of larger internal diameter, therebyleaving shoulders 56 perpendicular to the axis of the opening in theportion of smaller internal diameter. The closed end of the ejector 53,on opposite sides of the nose 54, is adapted to seat against theseshoulders 56 to limit the inward movement of the ejector, the nose 54being adapted to extend through a slot 57 in the portion of smallerinternal diameter. The ejector 53 is yieldingly urged inwardly by a coilspring 58 which seats at its outer end against the bottom of a recessprovided in the catch 59 in radial 'alinement with the tubular ejector.

The catch 59 is secured to the receiver by means of a threaded stud 60,this stud having a smooth extension adapted to extend into an opening inthe sleeve 11 to lock the sleeve in the receiver. wardly from the stud60 is a flexible arm provided with a lug 61 adapted to seat in anopening in the receiver, the rearwardly extending arm being sufiicientlyflexible to disengage the lug from the opening while Extending rearthestud 60 is being threaded into or out of the receiver. The spring recessin the forward end of the catch '59 opens downwardly through an opening62 in the lower side of the catch which is of substantially the samewidth as the diameter of the recess and which is substantiallyconcentric with the axis of the stud 60.

In assembling the ejector and catch, the

a catch is first secured to the receiver by 66 and a disconnector 67.pivotally mounted-in a frame 6 by means of threading the stud 60 intothe receiver, the catch being rotated slightly in advance (in aclockwise direction in Fig. 9) of its normal position, the ejector 53 isinserted into the opening 55, the spring 58 is seated in the axialrecess of the ejector, and the catch 59 is then rotated in acounterclockwise direction into the normal'position where the ejectorslidingly fits in the recess in the forward end of the catch and wherethe lug 61 snaps into the opening provided therefor in the receiver.

In operation, the nose of the ejector rides on the periphery of thecylindrical bolt until the slot (Fig. 14) reaches the ejector in therecoil of the bolt, whereupon the ejector nose rides down the inclinedslot under the influence of spring 58 into position to eject theemptycartridge case through the ejection opening 13. As the bolt movesforwaril, the ejector rides up the inclined groove 40 to the peripheryof the bolt, after which it rides on the periphery of the bolt, as thebolt continues its ,for- Ward reciprocation and then rotates into lockedposition.

The firing mechanism comprises a trigger 63, a trigger bar 64, a safetcatch 65, a scar he trigger 63 is pin 68. The trigger bar 64 has a notch69 (Figs. 15 and 16) at its .rearward 'end adapted to receive thetrigger and the trigger bar is yieldingly urged rearwardly bymeans ofcoil spring 69 abutting against'a' transverse 'web 70 of the frame 6 atits forward end and abutting the triggerbar at; its rearward;

end (Fig. 16').-

he trigger'bar 64 is fitted loosely through an opening in the trans-'verse web 70 of the -frame6 so that it may be inserted thereinafter-the triggerhas been assembled and so that it may upwardly endafter insertion, a spring 71 being provided yieldingly to urgeitupwardly. The sear 66 is formed as a bell crank pivoted onthe'transverse pin 72 which is journaled at its opposite ends independing lugs 75 (Fig. 3) on the receiver. The scar is normally urgedin a counterclockwise direction by the sear spring 7 3 which seats ontheupper end of the safety catch 65. In the normal position shown in thedrawings, adapted to engage the depending the firing'member to retainthe ber in retracted position. The disconnector lug of 67 comprises apin extending through a and locking sleeve. pin is rounded and engages aperipheral cam the hooked upper end of e moved and downwardly at itsforward,

' being cut into the sear is The upper end of this.

74 (Figs. 10 and 12) on the bolt, and

adapted to engage the receiver and prevent the pin from sliding too farintov the receiver chamber when the gun is inverted while the bolt isremoved, and from bein lost through the sear during mounting anddismounting. 1 A

The safety catch (Figs. 4, 6, 13, 15 and 16) comprises a cylindricalportion 75 surmounted by a flange 76 adapted to rest on the uppersurface of the frame 6. The catch is provided with a flat narrowedportion 77 extendin downwardly through the frame member y means of whichthe catch may be rotated, and with lugs 78 on the flange 76 engaging innotches in the frame to maintain it in safe and ready positions. The

cylindrical portion 75 is provided with a transverse opening to receivethe trigger bar 64, and to limit its rotation, and the trigger bar isprovided with a notch (Figs. 15 and 16). to hook over a shoulder of thecatch whenthe catch is in'the safe position shown in Fig. 15. The safetycatch is also vent the sear from being moved into firing position due tojarring the gun. Thus, the safety catch operates on both the trigger barand the sear, thereby affording a double precaution against accidentalfiring.

The means for lubricating the abutting surfaces between the locking lugshas been omitted in part in Figs. 4, 5 and 6 for the purpose of:clearness,

and the omitted parts.

provided with an upwardly extendinglug 79 adapted to underlie the rearend of the 'sear in the safe position of the catch to preare illustratedin Fig. 11. These parts comprise an annular duct 85 extending around.

two ducts 81- and 82 which extend, almost to the rear of the lockingsleeve, .the se ducts the outer periphery of the locking sleeve 11.Extending obliquely inwardly and forwardly from the ducts 81 and '82 arebranch ducts 83 and 84 which leadto theab'utting surfaces of the lockingThus lubricant may flow from the lu ricant cup 18 through theaxial duct80 in screw 17 to the annular duct 85,- thence rearwardly along theducts 81 and 82, and

ring memthence inwardlythrough ducts 83 and 84 to the abutting surfaces.

The preferredmeans for assembling the parts is as follows: In assemblingthe frame group the trigger is secured in the frame, the safety catch 65is inserted into position in the frame 6 from the top, the disconnectorspring 71 is inserted into its recess a hooking the forward end of therecoil spring into the rear end of the bolt, turning the. tube to theright relatively to the bolt to from the top, the spring 69 is placed onthe trigger bar, the triggerbar is inserted into the opening in the web70 from the rear and thence through the safety catch 65, and

' the rear end of the trigger bar is then 'interengaged with thetrigger.

as above described, and then mounting the sear on the depending lugs 75by means of the pin 72. The frame and receiver groups are attached tothe stock by means of the screws 16 and 17," and the lubricant cup 18 isthen threaded over the screw 17.

The bolt unit is assembled by slipping the sleeve 44 over the firing pinfrom the front, slipping the spring 47 over the. firing -pin from thefront and threading the constricted end of the spring over the collar48, sliding the sleeve" forwardly. on the firing pin against theactionof spring 47 and turning the sleeve to catch. over the downwardlyprojecting lug on the firing pin, inserting the firing pin unitinto thebolt from the I .rear and screwing the sleeve 44 into the bolt,

and then uncatching the firing pin from the rear face of the sleeve 44and permitting it to jump forward under the action of the spring 47, thelug 45 moving in'a longitu dinal slot on the lower side of the sleeve asshown in Fig. 6.

The recoil unit is assembled by mounting the buffer in the rear end ofthe recoil tube 4, slipping the shutter 29 into the recoil tube,inserting the recoil spring into the shutter, hooking the-rear end ofthe recoil spring into the rear end of the recoil tube,

twist the spring, then retracting. the bolt into the recoil tube withthe actuator 7 sliding down the slot 28 and hooking the actuator overthe shoulder provided at the rearward end of the slot 28 as shown inFig. 2.

V The bolt and recoil units, thus assembled together, are'then insertedinto the receiver from the rear, with the interrupted threads on thetube 4 (Fig. 17) clearing the interrupted threads ,at the rearward endof the part 3 of the receiver, and then turning the recoil tube to theright one-eighth turn to interengage the aforesaid interruptedthreads,-the stud 61 of the catch 59 locking thetwo parts of thereceiver against rota- 'The operation is as parts inthe position showninFigs. 5 and 6, the gun is ready to fire. Upon pulling the trigger, thetrigger bar 64 rocks the sear 66 in a clockwise direction until the lug45 of, the firing pin is -disengaged by the sear,

. engagement.

follows: With a..."

I whereupon the firing pin is shot forwardly the actuator lug 37 maymove freely along this oblique slot 27. After the bolt has rotatedsufliciently to clear the locking lugs from each other the actuatorv lug37 reaches the bend' in the slot 27, and in the continued rotation ,of.the bolt the movement of the lug 27 along this bend gradually blends therotary movement of the bolt into the purely reciprocatory movementacquired when the lug 37 reaches the longitudinal slot 28. In theunlocking rotation of the bolt, the cam 42 on the rear end of the boltengages the beveled face 46 on the firing pin lug and retracts thefiring pin, the firing pin being held retracted by the cam 42 during therecoil of the bolt. When the bolt again reaches forward position thefiring. pin lug 45 engages behind the sear 66 before the cam 42disengages the firing pin in the lock ingrotation of the bolt. Thefiring pin is prevented from rotating with the bolt by the lug 45extending through the slot 32in the receiver. In the locking movement ofthe bolt the firing pin lug 45 is 'accom-; modated by recess 33'extending in a counterclockwise direction from the slot 31. The tubularshutter '29 is caused to rotate with the bolt by the actuator-lug 37extending through the rectilinear slot 30.

and rotary motion of the bolt does not bring the lugs on the bolt andreceiver into However, when the lug 37 reaches thefioblique portion 27of the slot 27 which portionhas substantially the same obliquity as theabutting faces of the looking lugs, the locking lugs of" the bolt arecarriedinto engagement with the locking. lugs on the receiver.

In the unlocking movement of the bolt, the cam 74 (Figs. 10 and 12)moves the disconnector 67 downwardly, and the disconnector in turnmovesthe-trigger bar 64 downwardly below the. seafiso that the sear isreleased Whether or not'the trigger is released.

According to the present invention extensive locking surfaces betweenthe bolt and receiver are provi ed, and at the same time the weight andsize of the parts are kept within low limits. The bolt stroke andconsequently the receiver are short and the weights are well to therear. By dividing the receiver into two parts and interrelating theparts in the manner described, the 1 major portion of the receiver maybemade v very light, thereby greatly reducing "the total weight of thegun. By constructing and arranging the frame 6 as described, :it servesto form both the magazine and the trigger guard and also asupport forthe firing mechanism. I

I claim 1, A

gun comprising a. receiver, a breechclosure movably disposed in thereceiver to reciprocate rearwardly and forwardly and to rotate, at theforward end of its stroke into locked position, the receiver and closurehaving locking abutments arranged to interengage when the closurerotates into locked position, and having an interfitting lug andguideway to guide the closure, the locking abutments being inclined tothe line of breech pressure at suchangles as to hold the bolt closed athigh breech pressure and to slide relatively to each other when thepressure drops to a low vvalue automatically to unlock the closure, theguideway having a longitudinal portion and a transverse portiontangentially connecting with the longitudinal portion throughout agradual and uninterrupted bend so that the rotation of the closure intoand out of locked position blends with its reciprocation smoothlyandwithout impact, andthe lug and guideway being coordinated with thelocking abut-' ments so that the abutgnents are guided into and out oflocking engagement throughout a smoothly curving. path.

2. A gun comprising a receiver, abreech closure movably disposed in thereceiver to reciprocate rearwardly and forwardly and to rotate at theforward end of its stroke into locked, position, the receiver andclosure having locking abutments arranged tointerenga e when the closurerotates into locked position and having an interfitting lug and guidewayto guide the closure, the locking abutments being inclined to the lineofbreech pressure at such angles as to hold the bolt closed at highbreech pressure and to slide relatively to each other when the pressuredrops to a low value automatically to unlock the closure, the guidewayhaving a Longitudinal portion and a transverse portion tangentiallyconnecting with the longitudinal portion throughout a gradual anduninterrupted bend so that the rotationof the closure into and out oflocked positlon blends with its reciprocation smoothly and withoutimpact, and'said lug and guideway being interrelated with said abutmentsso.

that the bolt may be rotated through an angle at least of the order of110.

. 3. A gun comprising a receiver, a breech closure movably disposed inthe receiver to reciprocate rearwardly and forwardly and to rotate atthe forward end of its stroke into locked position, the receiver andclosure having locking abutments arranged to interengage when theclosure rotates into-locked position and having an interfitting lug andguideway to guide the closure, the locking abutments being inclined tothe 'line of breech pressure at such angles as to hold the bolt closedat high breech pressure and to so. i slide relatively to'each other whenthe-pres; sure drops to a low value automatically to to rotate at theforward-end of .its stroke into locked position, the receiver andclossure having locking abutments arranged to interengage when theclosure rotates into locked position and having an interfitting lug-andguideway to guide the closure, the

locking abutments being inclined to the line of breech pressure at suchangles as to hold the bolt closed at high breech pressure and toslide-relatively to each other when-the pressure drops to a low valueautomatically to unlock the closure, the guideway having a longitudinalportion and an oblique portion joined together by a gradual anduninterrupted bend so that the rotatio n of the 010-,

sure into and out of locked position blends with its reciprocationsmoothly and with-' out impact, said lug and guideway being interrelatedwith said locking. abutments so that said bend and oblique portionextend circumferentially through angles at least of v the order of 40and 70 respectively.

5. A ,gun comprising a receiver, a bolt adapted both to reciprocate andto rotate in the receiver, locking lugson the receiver and bolt adaptedto interengage when the bolt is rotated in one direction and todisengage when the bolt is rotated in the other direction, the engagingfaces of said lugs being inclined to the line of breech pressure at suchangle as to look the bolt closed at high breech pressure,and to sliderelatively to each other when thepressure drops to a low valueautomatically to unlockthe bolt, "and an interfitting'guiding lug andguideway on the bolt and receiver respec- -'tively, the guideway havinga longitudinal portion and an oblique portion inclined to theline ofbreech pressure substantially at said angle, so as to guide the bolt inits reciprocation and to rotate the bolt at the end of its forwardstroke to interengage said locking lugs, said longitudinal and obliqueportions being joined by a gradual bend extending through a widecircumfer- I ential angle so as smoothly to blend the reciprocatory androtary movements of the bolt, and the locking lugs beingcircumferentially separated from each other in the unlocked position of.the bolt by a wide angle so as to clear each other'during said blending.

6. A gun comprising a receiver, a bolt adapted to reciprocate rearwardlyand for wardly in the receiver and'to rotate into locked position at theforward end of its stroke, the receiver having a slot extendinglongitudinally of the gun throughout its rearward portion and incliningcircumferentially at its forward end, a lug on the bolt adapted to slidein said slot to guide the bolt in its reciprocatory and rotaryadapted toslide in said slot to guide thebolt in its reciprocatory and rotarymovement, and a shutter non-reciprocatable but rotatable with the boltto close said slot, said shutter having a longitudinal slot toaccommodate said lug.

8. A gun comprislng a receiver, a bolt adapted to reciprocate rearwardlyand forwardly in the receiver and to rotate into locked position at theforward end of its stroke, the receiver having a slot extendinglongitudinally of the gun throughout its rearward portion and incliningcircumferentially at its forward end, a lug on the bolt adapted to slidein said slot to guide the bolt in its reciprocatory and rotary movement,and a tubular shutter fitting between saidbolt'and said receiver forcover ing said slot, said shutter having a longi- .tudinal slot toaccommodate said lug.

9. A gun comprising a receiver, a bolt adapted to reciprocate rearwardlyand forwardly in the receiver and to rotate into locked position at theforward' end of its stroke, a firing member adapted to reciprocate withthe bolt, the receiver having a bolt slot extending longitudinally ofthe gun throughout its rearward portion and inclin- -wardly in .thereceiver and to rotate into locked position atthe forward end f itsstroke, a firing member adapted to reciprocate with the bolt, thereceiver having. a bolt slot extending longitudinally of the gunthroughout its rearward portion and inclining circumferentially at itsforward end, a

I lug on the bolt adapted to slidein said slot to guide the bolt in itsreciprocatory and rotary movement, said receiver also having a firingmember slot extending longitudinally'thereof, a lug on the firing memberextending through said last slot, and a tubular shutter fittingbetweensaid bolt and receiver for closing both of said slots when the bolt isin locked position, said shutter having slots to accommodate said lugs.

11. A gun comprising a receiver, a bolt adapted to reciprocaterearwardly and forwardly in the receiver and to rotate into lockedposition at the forward end of its stroke, a firing member adapted toreciprocate but not rotate with the bolt, the receiver having a boltslot extending longitudinally of the gun throughout itsrearward portionand inclining circumferentially at its forward end, a lug on the boltadapted to slide in said slot to guide the bolt in its reciprocatory androtary movement, said receiver also having a firing member slotextending longi-. tudinally thereof, a lug on the firing memberextending through said last slot, and a shutter arranged to rotate butnot reciprocate with said bolt for closing both of said slots when thebolt is in locked position, said shutter having slots arranged 'toregister with said receiver slots when the bolt is unlocked toaccommodate said lugs.

12. A gun comprising a receiver, a bolt adapted to reciprocaterearwardly andforwardly in the receiver and to rotate into lockedposition at the forward end of its stroke, a firing member arranged .toreciprocate but not rotate with the bolt, the re ceiver having a boltslot extending longitudinally of the gunthroughout its rearward portionand inclining circumferentially at its forward end, a lug on the boltadapted to slide in said slot to guide the bolt in its reciprocatory androtary movement, said re- .ceiver also having a firing member slotexslot, and a tubular shutter fitting between. said bolt and receiverfor closing said slots when the bolt is in locked position, said shutterbeing rotatable but non-reciprocatable with said bolt and having slotsfor said lugs arranged to register with said receiver slots when thebolt is unlocked, the shutter slot for the firing member lug having anoffset portion to permit rotation of the shutter with the bolt intolocked position.

13. A gun comprising a receiver, a bolt adapted to reciprocaterearwardly and forwardly in the receiver and to rotate into lockedposition at the end of its forward stroke, said bolt having a lug toguide its movements, the forward portion of said re-, ceiver connectingwith the barrel of the gun and the rearward portion comprising a tubethreaded 'to the forward portion, said portions havingintercommunicating slots to guide said lug, and a second tube rotatablewithin said first tube for closing said slots when the bolt is in lockedposition, said tube having a slot for said lug adapted to register withsaid slot when the bolt is unlocked, said second tube abutting at itsforward end against the rearward endof the forward portion of thereceiver and against the rearwagd end of said first tube at its rearwarden 14. A gun comprising a receiver, a bolt adapted to reciprocaterearwardly and forwardly in the receiver and to rotate into lockedposition at the end of its forward stroke, said bolt having a lug toguide its movements, the forward portion of said receiver connectingwith the barrel of the gun and the rearward portion comprising a tubesecured to the forward portion, said portions having intercommunicatingslots to guide said lug, and a second tube rotatable within said firsttube for closing said slots when the bolt is in locked'position, saidsecond tube having a slot for said lug adapted to register with the slotof said first tube when the bolt'is unlocked. v

15. A gun comprising a receiver, a bolt arranged to reciprocateforwardly and rearwardly in the receiver and to rotate into lockedposition at the forward end of its stroke, the bolt having a lug toguide its movement, the receiver comprising forward and rearwardportions connected end to end,

said portions having intercommunicating slots to guide said'lug, theslot in said rearward portion extending longitudinally of the gun toguide the reciprocationof the bolt and the slot in the forward portionbending circumferentially to rotate the bolt into and out of lockedposition, the forward portion having a thick wall to withstand thestresses incident to the rotation of the bolt and the rearward portionhaving a lesser thickness adapted merely to guide the bolt in itsreciprocatory movement.

16. A gun comprising a receiver having tubular forward and rearwardportions disposed endto end, a tubular locking member fitted into saidforward portion, said rearward portion being fitted into said forwardportion in abutting relationship to said member, and. a tubularshutter-rotatable in said rearward portion in abutting relationship tosaid member.

17. A gun comprising a receiver having tubular forward and rearwardportions disposed end to end, a tubular locking member fitted into saidforward portion, said rearward portion being fitted into said forwardportion in abutting relationship to said member, and a bolt movable insaid receiver into find out of lockingrelationship to said mem- 18. Agun comprising a receiver having tubular forward and rearward portionsdetachably fitted together end to end, a tubular locking memberfittedinto said forward. portion, and a bolt movable in said receiver into andout of locking relationship with respect to said member, said receiverand bolt having interlocking abutments adapted to lock the bolt inclosed position, and certain of said abutments having lubricant ductsleading to the abutting surfaces thereof.

19. A gun comprising a receiver, a bolt reciprocatableforwardly andrearwardly in the receiver and rotatableinto locked position at theforward end of its stroke, and sets of interengaging locking abutmentson the receiver and bolt respectively to lock the bolt in closedposition, one of said sets of abutments being provided with lubricantducts leading to the abutting faces thereof.

20. A gun comprising a receiver, a breech closure movably disposed inthe receiver to reciprocate rearwardly and forwardly and to rotate atthe forward end of its stroke into locked pos tion, the receiver andclosure having locking abut-ments arranged to interengage when theclosure rotates into locked position and having an interfitting lug andinterrelated with said abutments so that said bend extendscircumferentially through an angle at least of the order of one-half thecircumferential extent of said locking abutments.

21. A gun comprising a receiver, a breach closure movably disposed inthe receiver to reciprocate rearwardly and forwardly and to rotate atthe forward end of its. stroke into locked position, the receiver andclosure having locking abutments arranged tointerengage when the closurerotates into locked position and having an interfitting lug and guidewayto guide theclosure, the locking abutments being inclined to the line ofbreech pressure at such angles as to hold the bolt closed at high breechpressure and to slide relatively to each other when the pressure dropsto a low value automatically to unlock the closure, the guideway havinga longi- "tudinal portion and an oblique portion joined 15 said lug andguideway being interrelated 20 with said locking abutments so that saidbend and oblique portion extend circumferentiall'y through angles whoseratio is approximately four-sevenths.

Signed by me at Cleveland, Ohio, this 25 18th day of December, 1919.

oscAn v. PAYNE.

